The Cash App, by Square, is a handy, convenient app that allows you to pay friends and family without having to have actual cash on hand, or even be in the same room. 
It's a peer-to-peer payment app, that's simple to use. It's great for situations like splitting a pizza with some friends or requesting money from a friend, and both can be done digitally from your phone. 
How to add a credit card to your Cash App account on iPhone or Android phone

However, in order to do this you first have to link your bank or card to your Cash App account. If you don't link a card or bank account to your account you can still receive money, but you can't cash out or send money to others. You should note that Cash App does charge a 3% fee for sending money using a credit card.

Here's how link a bank account or a credit card to your Cash App.

1. Open the Cash App on your iPhone or Android phone.
2. Go to the "My Cash" tab by tapping the icon of a building in the lower-left corner.
Tap the building icon.
3. Under the options for "Cash and Bitcoin," tap the "+ Add Bank" option.
Go to the "My Cash" tab, and tap "+ Add Bank."
4. If you want to add a debit card, enter your card information in the pop-up screen, then tap "Add Card." After that, your bank should be linked.
5. If you don't have a debit card, tap "No Card?" to add your bank account.
Either enter your debit card number and tap "Add Card," or tap "No Card?" if you don't have a debit card.
6. Select your bank from the list of banks. Then enter your online banking username and password, and follow the on-screen instructions to link your account.

Select your bank, then follow the on-screen instructions

How to add a credit card to your Cash App

1. Open your Cash App.
2. Go to the "My Cash" tab by tapping the icon of a building in the lower-left corner.
3. Tap "+ Add Credit Card" under the name of your bank.
Go to the "My Cash" tab, then tap "+ Add Credit Card."
4. Enter your card information, then tap "Add Card." This will link the card to your account.